Slaughter: You might keep in mind that it is not only the US that uses Imperial [British Imperial typically, although America would like us to forget about that] standards. I am by no means American, but I've grown up (as has pretty much everybody I know) using pounds for human weight, feet and inches for human height and inches for measuring paper, wood, etc. That said, up here in the Great Frozen Wastelands of the North, we do use kilometers for driving distance, liters for liquids and so forth. It's really quite schizophrenic, once you write it all out.
If it is such extreme American arrogance to assume that all the world should use Imperial, is it not arrogance of a sort to assume that _only_ America uses Imperial?
It does seem highly unlikely that I will ever have a client request a print job with a size designation in anything other than feet and inches.